A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all rights under applicable copyright law.
1. Field of the Invention
The present invention relates generally to waste or recyclables collection systems and assemblies. More particularly, the invention relates to systems and assemblies which pack and then unload the waste or recyclables.
2. Background of the Invention and Prior Art
Refuse collection trucks are generally used for collection of trash and other refuse or recyclables. Typically, a refuse collection truck has a body which is supported by a chassis and wheels and which stores the refuse for transport. Rear loading refuse trucks also include a tailgate assembly mounted at the back-end portion of the truck. This tailgate assembly has a hopper for receiving refuse and an opening between the hopper and the body for transporting the refuse to the body. Typically, the tailgate assembly has a sweeping mechanism for pushing and compacting the refuse in the hopper before the packing mechanism forces the refuse into the body or storage area of the refuse collection truck. The packing and sweeping mechanisms work together as the compactor by forcing the fresh refuse against the old refuse into the body, thereby compacting the refuse within the body to a maximum density.
In general, it is necessary for the packing/sweeping mechanisms of this type of packer to have four travel paths. This is generally accomplished by having a packing panel which is pivotally attached to a carrier panel. The first and second paths accommodate the addition of fresh refuse into the hopper. From a position where the packer blade is holding the refuse in the body, the first path is having the packing blade rotate rearwardly up and over refuse piled in the hopper. This is called the unsweep cycle. The second path moves the carrier panel and packing blade down such that the blade is in a position above and behind the refuse. This is called the unpack cycle. The third part of the path is when the packing panel rotates toward the front of the truck. This is generally called the sweep motion as it sweeps material out of the rear of the hopper toward the front. The fourth portion is called the packing cycle. In this portion, material is moved up from its position in the bottom of the hopper to be packed into the body of the truck.
The object of the first two paths is to get the blade up and over the refuse in such a way as to not push the refuse back into the street and to allow the refuse to be built up as high in the hopper as possible. When the packing/sweeping mechanisms are in the packing mode or have stopped at the end of the packing mode, the packing/sweeping mechanisms are positioned to allow refuse into the hopper without obstruction. As the packing/sweeping mechanisms return to the contain mode, at the end of the pack cycle, they hold the refuse in the body and pack it against old refuse. As more and more material is packed into the body, the ejector panel gradually moves toward the front of the body until the body is full.
The hopper of the tailgate assembly is designed to receive refuse containers of varying sizes which are either hand-load operated or lift-mechanism operated. The hand-loading operation requires a refuse crew to collect the refuse in-hand and put it into the hopper of the refuse collection truck. The lift-mechanism operation uses a device to grab the refuse container, raise the container above the rear opening of the hopper and tilt the container sufficiently to dump all the refuse into the hopper.
The prior art rear loading types of packers that have an upper panel connected to a lower panel use several ways to control the movement of the panels. The first method is to have the upper panel slide in a groove and the lower panel rotates at its end controlled by a hydraulic cylinder connected between the two panels. Another method uses two sets of two forward projecting links connected at one of their ends to the tailgate and connected at their other ends to the upper panel. A typical representation of this method is shown in U.S. Pat. No. 3,999,669. This four-bar mechanism controls the motion of the upper panel. The lower panel rotates at its end controlled by a hydraulic cylinder connected between the two panels. Yet another method uses two sets of two rearward facing links connected at one of their ends to the tailgate and connected at their other ends to the upper panel. This four-bar mechanism controls the motion of the upper panel. The cylinder that controls the lower panel is connected between the tailgate and the lower panel. A representative example of this is shown in U.S. Pat. No. 5,478,188. Yet another method used to control the panels is to rotatably connect the upper panel to the tailgate on a single axis such that it can swing. The prior art attached the cylinder for moving the lower panel between the tailgate and the lower panel. A representative example of this is shown in U.S. Pat. No. 4,460,307.
The efficiency of a packer is based on the amount of refuse the packer can pack in what amount of time. Therefore, the swept volume and the cycle time are integral parts of the equation and should be optimized. The number of cycles or frequency of operation of the packing/sweeping mechanisms depends upon the capacity of the hopper. A large hopper can temporarily store a larger volume of refuse and accordingly, less time is lost while waiting for the packing/sweeping mechanisms to complete their cycle. The height of the sill at the tailgate opening is one factor that limits hopper capacity. The higher the refuse receiving opening is above the ground, the more effort is required by the workmen in dumping their containers into the hopper. Accordingly, the sill over which the refuse is dumped into the hopper should be as low as possible. In general it is desirable to have as light a collection vehicle as possible. It is desirable to have the overhang past the rear axle as short as possible. It is desirable to have as high a density packing as feasible. It is desirable to have the cycle time as quick as possible, especially the time from packing to being able to reload the hopper. There are also restrictions on height and width that must be maintained. There is also a minimum exit angle from the rear tires to the bottom of the hopper that should be maintained for ground clearance. It is also desirable to have a packer that has low maintenance and is inexpensive to build.
The prior art packers that use a slot to control the motion of the upper panel have the following deficiencies. The straight motion during the pack cycle means that the hopper floor will be flat in that area. Flat floors require additional stiffeners to support the pressure on them, thus increasing the weight of the tailgate. Slides are difficult to seal and therefore are prone to deteriorate more quickly than pivot style of bearings. Slides are also more difficult to support structurally than a single pivot, thus requiring more material and weight to do so. Also, the straight path during the packing cycle limits the hopper capacity somewhat. The blade tip must travel from the lowest point at the end of the sweep up to the hopper lip. If this path is curved there is more usable hopper volume than if it is straight.
The prior art that utilizes forward facing links has the following deficiencies. The amount of bearings to make this work is large. This again makes support of the bearings more difficult, adding weight. More bearings result in more maintenance problems. This method also has a hopper that has a major change of direction between the sweep and pack cycles. This wears the hopper out more quickly. This discontinuity also causes more problems with moving incompressible objects into the body and fall back is a greater problem. This prior art also uses a packing cylinder in the pull mode verses the push mode. This means that it does not make as good use of the available force as possible.
The prior art that utilizes rearward facing links has the following deficiencies. The amount of bearings to make this work is large. This again makes support of the bearings more difficult, adding weight. More bearings result in more maintenance problem, not only for the bearings themselves, but for the maintenance of parts they connect. This prior art also uses a packing cylinder in the pull mode verses the push mode. This means that it does not make as good use of the available force as possible.
The prior art that uses a swinging type of attachment for the upper panel is configured such that the motion of the panels on the unpack stroke tend to push material out of the hopper. The packer cylinders are pulling to pack and thus do not have the added force for the same pressure that pushing would give. In addition, high pressure is needed during the sweep and pack cycles. Cylinders that are pulling during the high pressure cycle are more likely to leak hydraulic fluid than those that push. The angle of incidence of the tip of the panel to the hopper is far from 90 degrees. This gives a tendency for the blade to ride up over the material in the hopper giving larger pressures in the cylinders.
Therefore, it would be highly advantageous to remedy the foregoing and other deficiencies inherent in the prior art.
In order to accomplish the desired objects of the invention with a preferred embodiment thereof, provided is a back-end mounted tailgate assembly with the included packing mechanism and a body with the included ejector system on a refuse collection truck. The tailgate assembly or hopper includes a hopper floor between two side walls. The hopper floor extends below the body floor. This allows the hopper to collect and hold incoming refuse. The upper and lower panels act together to do the packing and sweeping motions. The upper panel consists of a shield supported by a frame that extends between the hopper walls. The frame is rotatably mounted to the tailgate by a pair of upper panel spherical pivots which are located substantially above the hopper sill. The lower packing panel is pivotally connected to the upper panel by a pair of pivots. The lower panel consists of a blade, extended between the two side walls, which sweeps and then packs the refuse or other materials along the hopper floor up into the body. Slits in the side walls provide egress for a beam to which the packer cylinders attach on the outside of the tailgate. This provides the motion to the packer panel assembly.
The sweep cylinders attach between a pair of upper cylinder ears on the upper portion of the upper panel to a pair of ears on the rear portion of the lower panel. This cylinder configuration provides the motion for the lower panel relative to the upper panel.
It is necessary to position the pack cylinders against the exterior portion of the side walls or outside of the hopper in order to have a pack cylinder that pushes. This positioning prevents the pack cylinder from interfering with the intake of refuse.
The tailgate assembly is pivotally attached to the body at the top on each side. The tailgate opening cylinder is pivotally attached to the center of the roof of the body. The rod end of the cylinder is attached to one end of a link. The other end of the link pivots at the top header beam of the tailgate. The rotation of this link also rotates a torque tube that in turn pulls up on a rod and opens the latch at the bottom of the tailgate. This latch fixedly connects the bottom of the tailgate to the body during packing. There is also another link which is rotatably attached to the tailgate rearward of the link pivot. The other end of this link is slotted and is located between the afore mentioned tailgate link pivots. The rod end of the cylinder is also attached to slide within this slot. The motion of the packing mechanism is as follows. The sweep cylinder retracts, rotating the packer blade rearward. With a large rod this can be made to happen very fast. The packer cylinder retracts which rotates both panels and moves the packer blade into a position behind and above the refuse or other material. The sweep cylinder extends. If additional speed is desired, the cylinder can be made to regenerate during the first portion of the sweep and then kick out of regeneration when the higher force is needed. As the sweep cylinder extends, the packing panel rotates forward moving material toward the body opening. The packer cylinder extends, which raises both panels and pushes the refuse or other material into the body under high pressure. The material is pushed against the ejector panel which starts at the rear of the body. This gives a uniformly higher density to the packed refuse. As the pressure builds up, a valve allows the ejector to move forward until the whole body is packed full. To raise the tailgate to allow for dumping, the tailgate cylinder is retracted. The first link and the slotted end of the second link and the rod end of the cylinder rotate upwardly. The rotation of the first link opens the tailgate latches. When the rod end of the cylinder pivoted on the end of the first link reach the end of the slot, the latches have been opened and the cylinder has been raised up high enough to have sufficient moment arm to raise the tailgate. Pulling to raise the tailgate also resolves the problem of cylinder drift opening the tailgate. Most automatic unlatching tailgates use push motion to open and raise the tailgate. When the cylinders and valves wear, they tend to leak and when leakage occurs to a cylinder it generally extends. When this happens the tailgate opens.
With the tailgate opened the ejector panel is extended to the rear of the truck and the material is ejected from the body. The tailgate lift cylinder is extended and the tailgate shuts. When the tailgate is shut all of the way, the cylinder keeps extending which locks the tailgate locks and lowers the overall height of the cylinder.
Accordingly, it is an object of the present invention to provide a new and improved waste or recyclables collection system.
A further object of this invention is to produce a packer that will not push garbage out of the hopper on the return stroke. This is accomplished by having the pivot for the upper panel substantially over the sill of the hopper. This makes the return stroke such that the refuse that has been piled up in the hopper is pushed down against the bottom of the hopper rather than being pushed rearwardly out of the hopper. This also allows the present design to have a deeper hopper.
Another object of the present invention is to decrease cycle times and increase panel pressures by utilizing the inherent push and pull features of the sweep and pack cylinders to best advantage. The largest forces in the entire cycle are during the sweep and pack when refuse is being compacted. During the unsweep and unpack, maximum speed is desired and little force is required. By utilizing a packer cylinder that pushes instead of pulls, a large rod can be used. This gives the aforementioned advantages of a larger packing force for the same pressure and the large rod increases the return speed dramatically. The pack cylinder is also positioned such that the moment arm at the beginning of the pack cycle (when less compaction is needed) is smaller than the moment arm at the end of the pack cycle when maximum compaction is needed. Matching the required force to the actual force in this way also decreases the cycle time.
Another object of the invention is to reduce the weight of the packing mechanism, tailgate and associated parts. The mounting of the cylinder is unique in that it is mounted adjacent to the tailgate lock area. The tailgate lock area must be reinforced to transfer the packing loads into the body. By mounting the packing cylinder to this area which had already been reinforced, the need to reinforce another area was eliminated. Therefore, the overall weight is reduced. Another way weight reduction has been accomplished is in the design of the scraper panel. The scraper panel consists of a beam on the bottom that is pointed that scrapes material off of the upper panel as the packer goes through its motion. There are times when the force on the bottom beam of the scraper panel may be quite substantial. The area above the beam must also be sealed off so that refuse does not flow over the beam back into the tailgate, but instead is pushed into the body. The present invention has a sheet that is curved from side to side, welded to the top of this scraper beam. The sheet being curved holds the pressure against it from the inside of the body without the use of additional stiffeners. This is accomplished because the sheet is put into tension rather than having to take the pressure and bending. The additional benefit to curving the sheet this way is that it keeps the local buckling of the sheet from occurring which would then cause the lower scraper beam to fail.
A further object of the present invention is to be able to accommodate offset packing loads without increasing the weight of the structure. During packing, if the load is not centered in the hopper some of the load from the packer cylinder on the side away from the offset load needs to be transferred to the side where the offset load is. This is accomplished by designing the upper panel such that it can rotate around a substantially horizontal axis. This rotation allows the upper and packing panels to come against the side of the hopper on one side and the upper side of the upper panel comes against the other side of the hopper. This puts a force couple into the whole panel structure that offsets the couple induced by the offset load.
A further object of the present invention is to have less wear on the hopper floor. This is accomplished by three methods. First, as the packer panel goes through the sweep portion it comes to a point where it is almost tangential to the curve of the packer portion of the cycle. This means that the transition between the two is smooth and doesn""t put high forces on the hopper floor. Additionally, the packer panel is designed such that the angle of incidence of the tip of the panel against the floor is nearly 90 degrees. This provides more of a scooping action of the refuse going up the hopper than many other designs where the panel is trying to wipe over the refuse. The third method used for reducing the wear of the hopper is that during the packing portion of the cycle, the packer blade actually begins to diverge from the floor. This reduces the pressure on the hopper floor as the pack cycle continues, thus reducing the wear.
An additional object of the present invention is to provide a vertical mounting beam for bin lifters that is not an addition to the structure, thus adding weight.
A further object of the present invention is to produce a swept area that is almost square in cross section. The reason for this is that, for a four sided area, a square gives largest area for the same perimeter. Rounding of the path provides even more efficiency gains. Elongation of the swept crossectional area reduces the efficiency.
Another object of the present invention is to have a hopper that is easy to load. The square cross section of the swept volume gives a hopper that is much easier to fully load than any of the designs that have a more elongated swept volume.
Another object of the present invention is to increase the packing efficiency by reducing fall back of the packed material into the hopper. This is accomplished by having a small distance between the upper forward edge of the hopper and the tip of the packing panel. It is also accomplished by having the edge of the hopper lip higher than the floor of the body. This provides a xe2x80x9ccatchxe2x80x9d that holds onto the material and keeps it from falling back into the hopper.
Another object of the present invention is to maximize the number of tailgates that can fit in an overseas shipping container.
Another object of the present invention is to provide a tailgate that will fit various width bodies.
Another object of the present invention is to provide an automatic tailgate latch and opener with few cylinders, that will accommodate different widths and has a low mounting height.
Another object of the present invention is to simplify the hydraulic routing especially for shipping only tailgates. This is accomplished by mounting a single valve block on the tailgate itself.